Re: [RFC PATCH v2 07/47] hugetlb: add CONFIG_HUGETLB_HIGH_GRANULARITY_MAPPING

[Mike Kravetz]

On 10/21/22 16:36, James Houghton wrote:
> This adds the Kconfig to enable or disable high-granularity mapping.
> Each architecture must explicitly opt-in to it (via
> ARCH_WANT_HUGETLB_HIGH_GRANULARITY_MAPPING), but when opted in, HGM will
> be enabled by default if HUGETLB_PAGE is enabled.
> 
> Signed-off-by: James Houghton <jthoughton@xxxxxxxxxx>
> ---
>  fs/Kconfig | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/fs/Kconfig b/fs/Kconfig
> index 2685a4d0d353..ce2567946016 100644
> --- a/fs/Kconfig
> +++ b/fs/Kconfig
> @@ -267,6 +267,13 @@ config HUGETLB_PAGE_OPTIMIZE_VMEMMAP_DEFAULT_ON
>  	  enable HVO by default. It can be disabled via hugetlb_free_vmemmap=off
>  	  (boot command line) or hugetlb_optimize_vmemmap (sysctl).
>  
> +config ARCH_WANT_HUGETLB_HIGH_GRANULARITY_MAPPING
> +	bool
> +
> +config HUGETLB_HIGH_GRANULARITY_MAPPING
> +	def_bool HUGETLB_PAGE
> +	depends on ARCH_WANT_HUGETLB_HIGH_GRANULARITY_MAPPING

Might also need to make this depend on CONFIG_ARCH_WANT_HUGE_PMD_SHARE
as the vma local allocation will only happen in this case.

-- 
Mike Kravetz

> +
>  config MEMFD_CREATE
>  	def_bool TMPFS || HUGETLBFS
>  
> -- 
> 2.38.0.135.g90850a2211-goog
>